When the US Department of Agriculture last week said that results of a screening test had raised the possibility that a second cow in the United States was infected with bovine spongiform encephalopathy, investors took notice.
Shares in Bio-Rad Laboratories, the leading provider of BSE tests globally, increased 3 percent at market close last Thursday, the day the government agency reported that results from two rapid screening tests for BSE were inconclusive. The news led to concern that, almost a year to the day, the nation’s beef supply may have been contaminated from a cow with the disease. Bio-Rad closed Monday at $56.55, up nearly 6 percent since the markets opened on Thursday.
The cow at the center of this new concern was tested before its meat entered the food supply, but few other details were provided by the USDA. Government officials said the agency would perform additional testing at its National Veterinary Services Laboratories, the national BSE reference lab, with results expected later this week.
Although Bio-Rad is known as a market leader for BSE testing, executives said in a conference call earlier this month that the company’s revenues from the service were “in decline” due to competitive pricing in the marketplace. Company officials were not available for comment.
Bio-Rad, based in Hercules, Calif., said its BSE ELISA is the most widely used test in Europe for the indication.
Bio-Rad claims a 70 percent market share in the BSE post-mortem testing market, collecting a large portion of revenues from government agencies that mandate the use of a test.
“The amount of testing done worldwide has roughly been fixed,” an executive told analysts in the conference call after the company released its quarterly financials in early November. The company’s share of the test market has increased but revenue has not followed.
“We are renewing contracts at lower prices based on competition and what the customer wants to pay,” the executive said. “The situation has mitigated somewhat but there are many contracts coming up.”
According to its website, Bio-Rad’s BSE test is currently used for screening more than 60 percent of all animals tested throughout the world. The company supports governments and industry in BSE screening programs in 25 countries including Japan, Germany, and the United Kingdom. More than 20 million cattle worldwide have been tested using Bio-Rad’s BSE test, the company claims.
The test runs on an automated robotics platform with the capacity to process up to 1,000 samples in an eight-hour time period.
Bio-Rad is also the leading manufacturer of tests used for detecting related TSEs (transmissible spongiform encephalopathies), which include scrapie in sheep and goats and CWD (chronic wasting disease) in elk and deer.
In the US, there are seven laboratories testing for mad cow disease and all use Bio-Rad’s test, according to news reports.
Currently, there is no test available to detect BSE in living animals. Instead, veterinary pathologists are able to confirm the disease by conducting post-mortem microscopic examinations of brain tissue, or by using other testing methods to identify the abnormal form of prion protein (PrPres) found in the brains of infected cattle (see box below).
The tests are priced from a few dollars up to as much as $20 each, according to Barrett Slenning, an associate professor of production medicine at the College of Veterinary Medicine at North Carolina State University.
Slenning said the Holy Grail for this type of testing will be the ability to perform the analysis before the animal is slaughtered. He said the cattle industry may be able to leverage recent advances to introduce such testing within the next 10 years.
In the US, there is a deep knowledge on the cattle herd with pedigrees that go back at least 60 years, and the use of embryo transfer in cattle breeding has created a 30-year-old stockpile of genetic analysis, he said.
“We are lucky dealing with cattle in that the cow genome has recently been fully described,” he said. “This is a hot area for research for being able to do ante-mortem pre-testing and breed testing.”
Still, he said, there is more to be done. “We have a lot more to know, let alone how to potentially diagnose it,” he said.
But, he said, the global livestock industry is already very comfortable with testing.
“It’s imbued in the culture where a variety of testing is done through the process of raising the animals, going through the slaughter, and in the processing of the animal,” he said.
Bio-Rad’s life science group acquired the TSE ELISA technology in 1999 as part of a $210 million purchase of Pasteur Sanofi Diagnostics. It rolled out the test for purchase in 2000, applying it to mad cow disease and chronic wasting disease.
The company claims accuracy of greater than 95 percent on its tests, Brad Crutchfield, Bio-Rad vice president, told Reuters.
He said one out of every 240,000 double-positive tests was found to be a false positive after more sophisticated testing.
Through Nov. 14, the USDA’s animal and plant testing service has tested just over 113,000 cows in a new random testing program it began in June.
As BCW went to press, the USDA had not yet completed testing on the suspect cow.
— Mo Krochmal ([email protected])
BSE Testing Methods Include:
- Histology: Examination of sections of the brain under a microscope for spongiform encephalopathy, or the presence of prion-associated fibrils. This test takes approximately two to five days to complete.
- Immunohistochemistry: The microscopic examination of brain sections which have been stained to outline the fine structure of the brain. Staining occurs as a result of a process where sections of the brain have been treated with antibodies for proteins; the antibodies are linked to enzymes that exhibit a chemical reaction (staining) of the pathological features. This process takes two to three days to complete.
- Western Blot: A process in which brain material is homogenized, normal prion protein is destroyed by a protease, and the sample is electrophoretically separated in a gel, where remaining abnormal prion protein is immunologically detected. For example, antibodies to the prion protein are bound and then detected by a second antibody linked to an enzyme; and the bound enzyme reacts with a substrate resulting in staining or light emission from the membrane. This process requires one to two days to complete.
- Mouse Bioassay: A process whereby suspect brain material thought to contain the abnormal prion protein is injected into the brain of a mouse (intracerebral injection). Clinical signs of infection diagnose infectivity. This test is confirmed by other methods like histology and requires several months to complete.
- ELISA (enzyme-linked immunosorbent assay): A process in which brain material is homogenized, with normal prion protein being destroyed by a protease, and any remaining abnormal prion protein bound to the surface of a clear microtiter well and immunologically detected. The signal is detected by a spectrophotometer and results are output in a quantitative format. This testing procedure takes four hours to complete.